Hvordan er 1. trimester screeningsperformance for tvillinger i Danmark?
Se alle abstracts fra ISUOG, Berlin i sidste nummer af UOG.
Objectives
To assess the performance of the Danish first trimester screening program in twin pregnancies.
Methods
This study was a retrospective, nation‐wide, cohort study with data collected from the Danish Fetal Medicine Database and The Danish Cytogenetic Registry. The cohort included all twin pregnant women participating in the national first trimester screening program for Trisomy 21. The risk assessment was based on maternal age, thickness of the nuchal translucency and, if available, biochemical markers (β‐hCG and PAPP‐A). Trisomy 21 was diagnosed by genetic testing either prenatally by chorionic villus sampling or amniocentesis, or postnatally. The primary outcome was the proportion of fetuses with Trisomy 21 in twin pregnancies detected prenatally by first trimester screening.
Results
8812 twin pregnancies including 42 pregnancies (39 dichorionic, 3 monochorionic) with Trisomy 21 had a risk assessment performed between 2009 and 2017. Overall, the detection rate was 78.6% (95% confidence interval 66.2% ‐ 91.0%) for a false positive rate of 7.2% (95% CI: 6.7 ‐ 7.8%). For dichorionic twin pregnancies, the detection rate was 76.9% (95% CI: 63.7% ‐ 93.2%) for a false positive rate of 7.4% (95% CI: 6.8% ‐ 8.0%). The detection rate for pregnancies with a risk assessment based on maternal age and nuchal translucency only (missing data on biochemical markers, n = 4693) was 69.6% (95% CI: 50.8% – 88.4%) for a false positive rate of 7.3% (95% CI: 6.6%– 8.1%), whereas for pregnancies with a risk assessment based on all three parameters (n = 4119) the detection rate was 89.5% (95% CI: 66.7% – 98.7%) for a false positive rate of 7.3% (95% CI: 6.5% – 8.1%).
Conclusions
The detection rate of Trisomy 21 in twin pregnancies, seems as high as for singleton pregnancies, when using optimal screening techniques, but the false positive rate is nearly twice as high.